BGRT
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| ACPI |
|---|
| Fixed Tables |
| Differentiated Tables |
| Tools/Libs |
The Boot Graphics Record Table (BGRT) is an optional ACPI table which contains a pointer to the image that has been drawn during boot.
Table structure
| Offset (hex) | Length | Description |
|---|---|---|
| 00 | 4 | Signature 'BGRT' |
| 04 | 4 | Length of the table (in bytes, including header) |
| 08 | 1 | Revision |
| 09 | 1 | Checksum |
| 0a | 6 | OEM ID |
| 10 | 8 | OEM Table ID |
| 18 | 4 | OEM Revision |
| 1c | 4 | Creator ID |
| 20 | 4 | Creator revision |
| 24 | 2 | Version ID (must be 1) |
| 26 | 1 | Status |
| 27 | 1 | Image type |
| 28 | 8 | Image address |
| 30 | 4 | Image X offset |
| 34 | 4 | Image Y offset |
Fields
Status
Indicates the image's status.
| Bits | Description |
|---|---|
| 0 | Displayed |
| 1:2 | Orientation offset |
| 3:7 | Reserved (must be 0) |
Orientation offset:
- 0b00: no offset
- 0b01: 90º
- 0b10: 180º
- 0b11: 270º
Image type
0: Image is a bitmap
1-255: Reserved
Image address
64-bit physical address to an in-memory copy of the displayed image. It can be a 24 bit bitmap (0xRRGGBB) or a 32 bit bitmap (0xrrRRGGBB), where lowercase R means reserved.
Image offsets
Describes the offsets to the (X, Y) of the screen for the top left image corner.